The major objective of this project is to contribute to the understanding of neuropsychological processes underlying mental impairment associated with the aging process. The main hypothesis is that aging individuals are characteristically highly reactive to irrelevant stimulation from the environment and that this attention abnormality produces excessive levels of arousal. On the basis of this distraction-arousal hypothesis, we propose to carry out four experiments on the influence of a short-term memory task (phasic distraction) and a sustained cognitive task (sustained distraction) on event-related electrical brain activity (contingent negative variation or CNV), autonomic activity, attention, and performance. Type B CNV shape (gradual rise time) shown previously to be characteristic of young individuals who are distractable and who show a pattern of dysphoria to psychotropic drugs will be assessed as a possible individual difference variable that differentiates distractable and mildly depressed elderly people. A vasodilator substance will be assessed for its possible ameliorative effects on distraction processes in the aged.